Method of making spinel LI2MN204 compound

ABSTRACT

A method of producing spinel Li 2  Mn 2  O 4  from LiMn 2  O 4 , lithium metal and graphite. A mixture of black LiMn 2  O 4 , lithium metal and carbon powders is prepared at a 1:1 molar ratio of Li to LiMn 2  O 4  and a 1:9 weight ratio of carbon to LiMn 2  O 4 . Then, the mixture is heated at a temperature between 170° C. and 200° C. until spinel Li 2  Mn 2  O 4  is produced. Alternatively, Li and carbon may be reacted together to produce LiC 6  or LiC 12 . Then the LiC x  may be mixed and heated with LiMn 2  O 4  to produce spinel Li 2  Mn 2  O 4 .

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to methods of producing spinelLi₂ Mn₂ O₄, and particularly, but not by way of limitation, to methodsof producing spinel Li₂ Mn₂ O₄ for use as a cathode material inrechargeable lithium batteries.

2. Description of Related Art

Various types of rechargeable batteries are known in the art. One suchfamily of rechargeable batteries is the familiar nickel-cadmium (ni-cad)battery and another such family of rechargeable batteries is thenickel-metal-hydride battery. Yet another family of rechargeablebatteries utilize an anode fabricated of carbon in conjunction with acathode fabricated of a lithium based composition, such as LiCoO₂,LiNiO₂ or spinel Li₂ Mn₂ O₄. Because the batteries utilizing the lithiumbased compositions have a high discharge voltage of about 4 volts andthus an energy density about twice that of the nickel-cadmium or thenickel-metal-hydride batteries, the batteries utilizing the lithiumbased composition represent the state of the art in small-sizerechargeable batteries. New and improved rechargeable batteries areconstantly being sought, thus, the prior art is replete with lithiumbased compositions wherein the compositions are produced in variousways.

As an example, U.S. Pat. No. 5,196,279 issued to Tarascon discloses amethod of producing spinel Li₂ Mn₂ O₄ wherein LiMn₂ O₄ is reacted withLiI at low temperatures, or by refluxing LiMn₂ O₄ in an acetonitrilesolution of LiI.

As another example, Lithium Intercalation from Aqueous Solutions, J.Electrochem. Soc., Vol. 141, No. 9, September 1994, page 2310, authoredby W. Li, W. R. McKinnon and J. R. Dahn discloses a method of producingspinel Li₂ Mn₂ O₄ in an aqueous LiOH electrolyte, or by reacting LiOHwith LiMn₂ O₄ in a solid-state reaction.

Although spinel Li₂ Mn₂ O₄ cathodes formulated in accordance with thework described by W. Li, W. R. McKinnon, J. R. Dahn, Tarascon and othershave generally exhibited the desired physical qualities of a highdischarge voltage and thus a high energy density, new and improvedmethods of producing spinel Li₂ Mn₂ O₄ are desired which do not requirethe use of solvents or the use of relatively expensive compounds. It isto such an improved method for producing spinel Li₂ Mn₂ O₄ that thepresent invention is directed.

SUMMARY OF THE INVENTION

In accordance with the present invention, spinel Li₂ Mn₂ O₄ is producedhaving the desired physical qualities of a high discharge voltage andthus a high energy density without the use of solvents or relativelyexpensive compounds.

Broadly, spinel Li₂ Mn₂ O₄ is produced by mixing effective amounts ofLi, LiMn₂ O₄, and a material capable of acting as a host for Liintercalation to form a mixture containing a molar ratio ranging fromabout 0.1:1 to about 1.5:1 of Li to LiMn₂ O₄ and containing a weightratio ranging from about 1:15 to about 3:7 of the material capable ofacting as a host for Li intercalation to LiMn₂ O₄. The resulting mixtureof Li, LiMn₂ O₄, and the material capable of acting as a host for Liintercalation is heated at a temperature of at least about 170° C. butno more than about 400° C. for a period of time effective to producespinel Li₂ Mn₂ O₄.

It should be noted that the presence of the material capable of actingas a host for lithium intercalation is critical in the reactiondescribed above. That is, a solid state reaction between Li and LiMn₂ O₄in the absence of the material capable of acting as a host for Liintercalation does not produce the desired spinel Li₂ Mn₂ O₄.

An object of the present invention is to provide an improved method ofproducing spinel Li₂ Mn₂ O₄.

Another object of the present invention while achieving the beforestated object, is to provide a method of producing spinel Li₂ Mn₂ O₄without the use of solvents.

Other objects, features and advantages of the present invention areapparent from the following detailed description when read inconjunction with the accompanying drawings and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional, fragmental, schematic representation of thecrystalline structure of a rechargeable lithium battery cell.

FIG. 2 is a flow chart illustrating a method of producing spinel Li₂ Mn₂O₄ from Li, LiMn₂ O₄ and a material capable of acting as a host for Liintercalation in accordance with the present invention.

FIG. 3 is a flow chart illustrating a method of producing spinel Li₂ Mn₂O₄ from Li, Lonza graphite and LiMn₂ O₄ by first producing lithiatedcarbon of the formula LiC_(x), wherein x ranges between about 6 to about48.

FIG. 4 is a flow chart illustrating a method of producing spinel Li₂ Mn₂O₄ from LiC_(x) wherein x ranges between about 6 to about 48, and LiMn₂O₄.

FIG. 5 is a chart illustrating the charge curves (solid lines) anddischarge curves (dashed lines) of spinel Li₂ Mn₂ O₄ prepared fromreacting (A) LiMn₂ O₄, Li and Lonza graphite at 200° C., (B) LiMn₂ O₄and LiI in acetonitrile solution at 80° C.

FIG. 6 is a chart illustrating the Raman spectra of the resultingproducts produced by heating a mixture of Li, Lonza graphite and LiMn₂O₄ at temperatures between 170° C. and 400° C.

FIG. 7 is a chart illustrating the Raman spectra of the resultingproduct produced by reacting Li and LiMn₂ O₄ with (A) Lonza graphite at10% by weight, (B) carbon (Super S) at 30% by weight, and (C) Li/LiMn₂O₄ molar ratio at 1.5:1 with Lonza graphite/LiMn₂ O₄ weight ratio at1:9.

FIG. 8 is a chart illustrating the Raman spectra of spinel Li₂ Mn₂ O₄prepared by reacting (A) LiC₁₂ and LiMn₂ O₄, (B) LiC₆ and LiMn₂ O₄, and(C) LiI and LiMn₂ O₄ in acetonitrile solvent.

FIG. 9 is a chart illustrating the X-ray diffraction data of (A) spinelLi₂ Mn₂ O₄ prepared by reacting LiMn₂ O₄, Li and Lonza graphite at 200°C., (B) spinal Li₂ Mn₂ O₄ prepared by reacting LiMn₂ O₄ and LiI in anacetonitrile solution at 80° C., and (C) LiMn₂ O₄ prepared from reactingMnO₂ and Li₂ CO₃ in air at 800° C.

FIG. 9A is a legend for the chart of FIG. 9.

DETAILED DESCRIPTION

Referring to the drawings in general, and to FIG. 1 in particular, showntherein and designated by the general reference numeral 10 is arechargeable lithium battery cell. The battery cell 10 includes a carbonanode 12, an electrolyte 14 and a composite cathode 16 fabricated ofspinel Li₂ Mn₂ O₄.

The carbon anode 12 of the rechargeable lithium battery cell 10 isprovided with a crystalline structure having a carbon framework 18. In asimilar fashion, the cathode 16 of the rechargeable lithium battery cell10 is provided with a crystalline structure having an Mn₂ O₄ framework20 defining a plurality of open channels therebetween. One of the openchannels is designated in FIG. 1 by the reference numeral 21 and isgenerally representative of the open channels of the cathode 16.

The electrolyte 14 is typically an electrolyte solution produced bymixing effective amounts of ethylene carbonate, and dimethyl carbonateto form a solution containing a 1:1 weight ratio of ethylene carbonateto dimethyl carbonate. Then, an effective amount of lithium perchlorateis dissolved in the solution of ethylene carbonate and dimethylcarbonate to form the electrolyte solution having a molar ratio of 1:1of lithium perchlorate to the solution of ethylene carbonate anddimethyl carbonate.

During the charring cycle of the battery cell 10, manganese begins tooxidize and Li⁺ ions are shuttled from the cathode 16 to the carbonanode 12 and intercalated therein to form Li_(x) C₆ wherein x rangesfrom about 0 to about 2. In FIG. 1, the intercalation of the Li⁺ ionsduring the charging cycle is indicated by the dashed circles, such asthe one designated by the reference numeral 22.

During the discharging cycle of the battery cell 10, Li⁺ ionsintercalate in the opposite direction, i.e. from the carbon anode 12 tothe spinel Li₂ Mn₂ O₄ cathode 16 and the manganese begins to reduce. InFIG. 1, the intercalation of the Li⁺ ions during the discharging cycleof the battery cell 10 is illustrated by solid circles, such as the onedesignated by the reference numeral 24.

Methods for producing Li based composition batteries, such as thebattery cell 10, are well known in the prior art. For example, a methodfor producing a Li based composition battery is disclosed in U.S. Pat.No. 5,196,279 issued to Tarascon. Thus, no further explanation is deemednecessary to teach one skilled in the art to produce a Li basedcomposition battery, such as the battery cell 10.

Referring to FIG. 2, broadly, spinel Li₂ Mn₂ O₄ can be produced bymixing effective amounts of Li, LiMn₂ O₄, and a material capable ofacting as a host for lithium intercalation at ambient conditions to forma mixture containing a molar ratio ranging from about 0.1:1 to about1.5:1 of Li to LiMn₂ O₄ and containing a weight ratio ranging from about1:15 to about 3:7 of the material capable of acting as a host for Liintercalation to LiMn₂ O₄ (FIG. 2, block 2.1). The resulting mixture ofLi, LiMn₂ O₄, and the material capable of acting as a host for Liintercalation is heated at a temperature of at least about 170° C. butno more than about 400° C. for a period of time effective to producespinel Li₂ Mn₂ O₄ (FIG. 2, block 2.2).

The term "material capable of acting as a host for Li intercalation", asused herein, refers to any material which will function as a host for Liintercalation and which will not produce any adverse effects in theproduction of spinel Li₂ Mn₂ O₄ by the methods disclosed herein.Examples of materials which will function as a "material capable ofacting as a host for Li intercalation" are carbons, such as Lonzagraphite and carbon (Super S).

The term "period of time effective to produce spinel Li₂ Mn₂ O₄ ", asused herein, refers to a period of time which can vary widely and anyperiod of time effective to produce spinel Li₂ Mn₂ O₄ can be utilized inthe practice of the present invention. Typically, however, the "periodof time effective to produce spinel Li₂ Mn₂ O₄ " typically rangesbetween about 12 hours to about 96 hours, and desirably ranges betweenabout 40 hours to about 60 hours, and more desirably ranges betweenabout 46 hours to about 50 hours.

Another method for producing spinel Li₂ Mn₂ O₄ is to mix effectiveamounts of Li and carbon to form a mixture containing a molar ratioranging between about 1:84 to about 1:4 of Li to carbon (FIG. 3, block3.1). The mixture of Li and carbon is then heated at a temperature of atleast about 170° C., but not more than about 400° C. for a period oftime effective to produce LiC_(x), wherein x ranges between about 6 toabout 48 (FIG. 3, block 3.2). Effective amounts of LiC_(x), and LiMn₂ O₄are then mixed together to form a mixture containing a molar ratioranging between 0.1:1 to about 1.5:1 of LiC_(x) to LiMn₂ O₄ (FIG. 3,block 3.3) and the mixture of LiC_(x) and LiMn₂ O₄ is then heated to atleast about 170° C., but not more than about 400° C. for a period oftime effective to produce spinel Li₂ Mn₂ O₄, as hereinbefore defined(FIG. 3, block 3.4).

The term "carbon", as used herein, refers to any carbon which willfunction as a host for Li intercalation and which will not produce anyadverse effects in the production of spinel Li₂ Mn₂ O₄ by the methodsdisclosed herein. Examples of carbons which will function as a "carbon",as used herein, are Lonza graphite and carbon (Super S).

The term "a period of time effective to produce LiC_(x) ", as usedherein, refers to a period of time which can vary widely and any periodof time effective to produce LiC_(x) can be utilized in the practice ofthe present invention. Typically, however, the "period of time effectiveto produce LiC_(x) " ranges between about 12 hours to about 96 hours,and desirably ranges between about 40 hours to about 60 hours, and moredesirably ranges between about 46 hours to about 50 hours.

Yet another method for producing spinel Li₂ Mn₂ O₄ is to mix effectiveamounts of LiC_(x) and LiMn₂ O₄ to form a mixture containing a molarratio ranging between 0.1:1 to about 1.5:1 of LiC_(x) to LiMn₂ O₄ (FIG.4, block 4.1). The mixture of LiC_(x) and LiMn₂ O₄ is then heated to atleast about 170° C., but not more than about 400° C. for a period oftime effective to produce spinel Li₂ Mn₂ O₄, as hereinbefore defined(FIG. 4, block 4.2).

In order to more fully describe the methods recited above for producingspinel Li₂ Mn₂ O₄ the following examples are set forth. However, it isto be understood that the examples are for illustrative purposes onlyand are not to be considered as limiting the present invention asrecited in the appended claims.

EXAMPLE 1

Spinel Li₂ Mn₂ O₄ was produced in accordance with the present inventionas follows. Black LiMn₂ O₄, Li metal and Lonza graphite powders weremixed together at ambient conditions to form a mixture containing amolar ratio of 1:1 of Li to LiMn₂ O₄ and a weight ratio of 1:9 of Lonzagraphite to LiMn₂ O₄. Samples of the mixture of LiMn₂ O₄, Li and Lonzagraphite were then heated in a sealed stainless steel reactor at 170° C.for 96 hours; at 200° C. for 48 hours; at 300° C. for 48 hours; and at400° C. for 48 hours.

Each of the samples produced by the method recited above was thenexamined under a Raman microscope and an X-ray diffractometer. Thesamples prepared at 170° C. (below the 186° C. melting point of Li) and200° C. showed some light-brown regions having Raman spectra with fourbands centered at 608, 400, 279 and 254 cm⁻¹ (curves A and B of FIG. 6).These Raman spectra are the same as those observed for spinel Li₂ Mn₂ O₄produced from LiI and LiMn₂ O₄ in acetonitrile solvent at 82° C., with amolar ratio of LiI to LiMn₂ O₄ of 6:1 (curve A of FIG. 8).

The Raman spectrum of the sample prepared at 300° C. (curve C of FIG. 6)demonstrated mainly the same features of the spinel Li₂ Mn₂ O₄ producedin accordance with the teachings of Tarascon. However, in addition tothe features of spinel Li₂ Mn₂ O₄, two weak impurity bands appear at 484and 425 cm⁻¹ (curve C of FIG. 6).

The Raman spectrum of the sample prepared at 400° C. (curve D of FIG.6), did not show obvious spinel Li₂ Mn₂ O₄ bands. Thus, it was concludedthat spinel Li₂ Mn₂ O₄ can best be prepared by this method in atemperature range varying between about 170° C. to 300° C.

Curve A of FIG. 9 is the X-ray diffraction data for the sample preparedat 200° C. Also shown in FIG. 9 is X-ray diffraction data of spinel Li₂Mn₂ O₄ prepared from reacting LiMn₂ O₄ and LiI in acetonitrile solutionat 80° C. (curve B) and X-ray diffraction data of LiMn₂ O₄ prepared fromMnO₂ and Li₂ CO₃ in air at 800° C. (curve C).

A battery, such as the rechargeable lithium battery cell 10, wasconstructed such that the cathode 16 of the battery was fabricated ofthe spinel Li₂ Mn₂ O₄ prepared at 200° C. Curve A of FIG. 5 is thecharge curve and curve A' is the discharge curve of such battery. CurveB of FIG. 5 is the charge curve and curve B' is the discharge curve ofthe rechargeable lithium battery cell 10 having the composite cathode 16fabricated of spinel Li₂ Mn₂ O₄ prepared by reacting LiMn₂ O₄ and LiI inacetonitrile solution at 80° C.

EXAMPLE 2

Black LiMn₂ O₄, Li metal and carbon (Super S) powders were mixedtogether at ambient conditions to form a first mixture containing amolar ratio of 1:1 of Li to LiMn₂ O₄ and a carbon (Super S) content of10 wt %. The first mixture was then heated in a sealed stainless steelreactor at 200° C. for 48 hours. Although the Raman spectrum of thefirst mixture (curve B of FIG. 7) did not show obvious spinel Li₂ Mn₂ O₄bands, X-ray diffraction data (not shown) indicated the presence ofspinel Li₂ Mn₂ O₄.

A second mixture of black LiMn₂ O₄, Li metal and carbon (Super S)powders was mixed together at ambient conditions. The second mixturecontained a molar ratio of 1:1 of Li to LiMn₂ O₄ and a carbon (Super S)content of 30 wt %. The second mixture of LiMn₂ O₄, Li metal and carbon(Super S) was heated in a sealed stainless steel reactor at 200° C. for48 hours.

The Raman spectrum of the second mixture was the same as the Ramanspectrum of the first mixture and thus, did not show obvious spinel Li₂Mn₂ O₄ bands. It was concluded that spinel Li₂ Mn₂ O₄ is produced invery small yields when carbon (Super S) was used for the materialcapable of acting as a host for Li intercalation.

EXAMPLE 3

Black LiMn₂ O₄, metal and Lonza graphite powders were mixed together atambient conditions to form a mixture containing a molar ratio of 1.5:1of to LiMn₂ O₄ and a weight ratio of 1:9 of Lonza graphite to LiMn₂ O₄.The mixture of LiMn₂ O₄, Li and Lonza graphite was then heated in asealed stainless steel reactor at 200° C. for 48 hours.

As illustrated curve C of FIG. 7, some impurity phases were present inthe corresponding Raman spectrum of the spinel Li₂ Mn₂ O₄ produced fromsuch mixture. Thus, it was concluded that a 1:1 molar ratio is preferredover a 1.5:1 molar ratio of Li to LiMn₂ O₄.

EXAMPLE 4

Black LiMn₂ O₄, Li metal and Lonza graphite powders were mixed togetherat ambient conditions to form a mixture containing a molar ratio of 1:1of Li to LiMn₂ O₄ and a weight ratio of 3:7 of Lonza graphite to LiMn₂O₄. The mixture of LiMn₂ O₄, Li and Lonza graphite was then heated in asealed stainless steel reactor at 200° C. for 48 hours.

X-ray diffraction data (not shown) revealed that the 3:7 Lonzagraphite/LiMn₂ O₄ ratio yielded less spinel Li₂ Mn₂ O₄ than the 1:9Lonza graphite/LiMn₂ O₄ ratio. Thus, it was concluded that a 1:9 ratioof Lonza graphite to LiMn₂ O₄ is preferred over a 3:7 ratio.

EXAMPLE 5

Li metal and Lonza graphite powders were mixed at ambient conditions toform a mixture containing a molar ratio of 1:6 of Li to Lonza graphite.Then, the mixture of Li and Lonza graphite was heated at a temperatureof 200° C. for 48 hours to produce LiC₆.

The LiC₆ produced from the Li metal and Lonza graphite powders was mixedwith LiMn₂ O₄ at ambient conditions by use of a pestle and mortar in aglove box filled with ultrahigh pure argon gas to form a mixturecontaining a molar ratio of 1:1 LiC₆ to LiMn₂ O₄. The mixture of LiC₆and LiMn₂ O₄ was then sealed in a stainless steel reactor and heated at200° C. for 48 hours to produce spinel Li₂ Mn₂ O₄.

Referring to FIG. 8, curve A is the Raman spectrum for standard spinelLi₂ Mn₂ O₄. Curve B is a Raman spectra for products formed from reactingLiC₆ with LiMn₂ O₄. A comparison of curves A and B shows that spinelLiMn₂ O₄ is produced from reacting LiC₆ with LiMn₂ O₄.

EXAMPLE 6

Li metal and Lonza graphite powders were mixed at ambient conditions toform a mixture containing a molar ratio of 1:12 of Li to Lonza graphite.Then, the mixture of Li and Lonza graphite was heated at a temperatureof 200° C. for 48 hours to produce LiC₁₂.

The LiC₁₂ produced from the Li metal and Lonza graphite powders wasmixed with LiMn₂ O₄ at ambient conditions by use of a pestle and mortarin a glove box filled with ultrahigh pure argon gas to form a mixturecontaining a molar ratio of 1:1 LiC₁₂ to LiMn₂ O₄. The mixture of LiC₁₂and LiMn₂ O₄ was then sealed in a stainless steel reactor and heated at200° C. for 48 hours to produce spinel Li₂ Mn₂ O₄.

Referring to FIG. 8, curve A is the Raman spectrum for standard spinelLi₂ Mn₂ O₄. Curve c is the Raman spectra for products formed fromreacting LiC₁₂ with LiMn₂ O₄. A comparison of curves A and C shows thatspinel Li₂ Mn₂ O₄ is produced from reacting LiC₁₂ with LiMn₂ O₄.

It should be appreciated that the laboratory procedures disclosedhereinabove may be adapted to commercial production of spinel Li₂ Mn₂O₄. Further, it is well within the scope of the present invention thatthe methods disclosed herein may be modified by the application of thewide variety of commercial production techniques which are known in theart.

Changes may be made in the combinations, operations and arrangements ofthe various parts and elements described herein without departing fromthe spirit and scope of the invention as defined in the followingclaims.

What is claimed is:
 1. A method for producing spinel Li₂ Mn₂ O₄comprising the steps of:(a) mixing effective amounts of Li metal, LiMn₂O₄ and a material capable of acting as a host for Li intercalation toform a mixture containing a molar ratio ranging from about 0.1:1 toabout 1.5:1 of Li metal to LiMn₂ O₄ and containing a weight ratioranging from about 1:15 to about 3:7 of the material capable of actingas a host for Li intercalation to LiMn₂ O₄ ; and (b) heating the mixtureof Li metal, LiMn₂ O₄ and the material capable of acting as a host forlithium intercalation at a temperature of at least about 170° C., butnot more than about 400° C. for a period of time effective to producespinel Li₂ Mn₂ O₄.
 2. The method of claim 1 wherein the material capableof acting as a host for Li intercalation is a carbon.
 3. The method ofclaim 1 wherein the mixture of Li metal, LiMn₂ O₄ and the materialcapable of acting as a host for Li contains a molar ratio of about 1:1of Li metal to LiMn₂ O₄.
 4. The method of claim 1 wherein the materialcapable of acting as a host for Li intercalation is a carbon and whereinthe mixture of Li metal, LiMn₂ O₄ and the carbon contains a weight ratioof about 1:9 of the carbon to LiMn₂ O₄.
 5. The method of claim 1 whereinthe mixture of Li metal, LiMn₂ O₄ and the material capable of acting asa host for Li intercalation is heated at a temperature of about 200° C.and wherein the period of time effective to produce spinel Li₂ Mn₂ O₄ isabout 48 hours.
 6. The method of claim 1 wherein the material capable ofacting as a host for Li intercalation is Lonza graphite and wherein themixture of Li metal, LiMn₂ O₄ and Lonza graphite contains a molar ratioof about 1:1 of Li metal to LiMn₂ O₄ and a weight ratio of about 1:9 ofLonza graphite to LiMn₂ O₄ and wherein the mixture of Li metal, LiMn₂ O₄and Lonza graphite is heated at a temperature of about 200° C. andwherein the period of time effective to produce spinel Li₂ Mn₂ O₄ isabout 48 hours.
 7. A method for producing spinel Li₂ Mn₂ O₄ comprisingthe steps of:(a) mixing effective amounts of Li metal, and a carbon toform a mixture containing a molar ratio ranging between about 1:84 toabout 1:4 of Li to carbon; (b) heating the mixture of Li metal and thecarbon at a temperature between about 170° C. and 400° C. for a periodof time effective to produce LiC_(x), wherein x ranges between about 6to about 48; (c) mixing effective amounts of LiC_(x) and LiMn₂ O₄ toform a mixture containing a molar ratio ranging between 0.1:1 to about1.5:1 of LiC_(x) to LiMn₂ O₄ ; and (d) heating the mixture of LiMn₂ O₄and LiC_(x) to a temperature between about 170° C. to about 400° C. fora period of time effective to produce spinel Li₂ Mn₂ O₄.
 8. The methodof claim 7 wherein the carbon is Lonza graphite.
 9. The method of claim7 wherein the mixture of Li metal and carbon is heated at a temperatureof about 200° C. and wherein the period of time effective to produceLiC_(x) is about 48 hours.
 10. The method of claim 7 wherein the carbonis Lonza graphite and wherein the mixture of Li metal and Lonza graphitecontains a molar ratio of 1:6 of Li to Lonza graphite.
 11. The method ofclaim 7 wherein the mixture of LiC_(x) and LiMn₂ O₄ contains a molarratio of about 1:1 of LiC_(x) to LiMn₂ O₄.
 12. The method of claim 7wherein the mixture of LiC_(x) and LiMn₂ O₄ contains a molar ratio ofabout 1:1 of LiC_(x) to LiMn₂ O₄ and wherein the mixture of LiC_(x) andLiMn₂ O₄ is heated to a temperature of about 200° C. and wherein theperiod of time effective to produce spinel Li₂ Mn₂ O₄ is about 48 hours.13. The method of claim 7 wherein the carbon is Lonza graphite andwherein the mixture of Li metal and Lonza graphite contains a molarratio of about 1:6 of Li metal to Lonza graphite and wherein the mixtureof Li metal and carbon is heated at a temperature of about 200° C. andwherein the period of time effective to produce LiC_(x) is about 48hours and wherein the mixture of LiC_(x) and LiMn₂ O₄ contains a molarratio of about 1:1 of LiC_(x) to LiMn₂ O₄ and wherein the mixture ofLiC_(x) and LiMn₂ O₄ is heated to a temperature of about 200° C. andwherein the period of time effective to produce spinel Li₂ Mn.sub. O₄ isabout 48 hours.
 14. A method for producing spinel Li₂ Mn₂ O₄ comprisingthe steps of:(a) mixing effective amounts of LiC_(x), wherein x rangesbetween about 6 to about 48, and LiMn₂ O₄ to form a mixture containing amolar ratio ranging between 0.1:1 to about 1.5:1 of LiC_(x) to LiMn₂ O₄; and (b) heating the mixture of LiMn₂ O₄ and LiC_(x) to a temperaturebetween about 170° C. to about 400° C. for a period of time effective toproduce spinel Li₂ Mn₂ O₄.
 15. The method of claim 14 wherein themixture of LiC_(x) and LiMn₂ O₄ contains a molar ratio of about 1:1 ofLiC_(x) to LiMn₂ O₄.
 16. The method of claim 14 wherein the mixture ofLiC_(x) and LiMn₂ O₄ contains a molar ratio of about 1:1 of LiC_(x) toLiMn₂ O₄ and wherein the mixture of LiC_(x) and LiMn₂ O₄ is heated to atemperature of about 200° C. and wherein the period of time effective toproduce spinel Li₂ Mn₂ O₄ is about 48 hours.
 17. The method of claim 14wherein the mixture of LiC_(x) and LiMn₂ O₄ is heated to a temperatureof about 200° C. and wherein the period of time effective to producespinel Li₂ Mn₂ O₄ is about 48 hours.